Showing posts with label WebSockets Tutorial. Show all posts

Sunday, March 19, 2017

WebSockets - Overview

In literal terms, handshaking can be defined as gripping and shaking of right hands by two individuals, as to symbolize greeting, congratulations, agreement or farewell. In computer science, handshaking is a process that ensures the server is in sync with its clients. Handshaking is the basic concept of Web Socket protocol.
The following diagram shows the server handshake with various clients −

WebSockets - Duplex Communication

Before diving to the need of Web sockets, it is necessary to have a look at the existing techniques, which are used for duplex communication between the server and the client. They are as follows −

Polling
Long Polling
Streaming
Postback and AJAX
HTML5

WebSockets - Implementation

Web Sockets occupy a key role not only in the web but also in the mobile industry. The importance of Web Sockets is given below.

Web Sockets as the name indicates, are related to the web. Web consists of a bunch of techniques for some browsers; it is a broad communication platform for vast number of devices, including desktop computers, laptops, tablets and smart phones.

WebSockets - Events & Actions

It is necessary to initialize the connection to the server from client for communication between them. For initializing the connection, creation of Javascript object with the URL with the remote or local server is required.

WebSockets - Opening Connections

Once a connection has been established between the client and the server, the open event is fired from Web Socket instance. It is called as the initial handshake between client and server.
The event, which is raised once the connection is established, is called the onopen. Creating Web Socket connections is really simple. All you have to do is call the WebSocket constructor and pass in the URL of your server.

WebSockets - Handling Errors

Once a connection has been established between the client and the server, an open event is fired from the Web Socket instance. Error are generated for mistakes, which take place during the communication. It is marked with the help of onerror event. Onerror is always followed by termination of connection.

WebSockets - Send & Receive Messages

The Message event takes place usually when the server sends some data. Messages sent by the server to the client can include plain text messages, binary data, or images. Whenever data is sent, the onmessage function is fired.

WebSockets - Closing a Connection

Close event marks the end of a communication between the server and the client. Closing a connection is possible with the help of onclose event. After marking the end of communication with the help of onclose event, no messages can be further transferred between the server and the client. Closing the event can occur due to poor connectivity as well.

WebSockets - Server Working

A Web Socket server is a simple program, which has the ability to handle Web Socket events and actions. It usually exposes similar methods to the Web Socket client API and most programming languages provide an implementation. The following diagram illustrates the communication process between a Web Socket server and a Web Socket client, emphasizing the triggered events and actions.

API – Definition

API, an abbreviation of Application Program Interface, is a set of routines, protocols, and tools for building software applications.
Some important features are −

WebSockets - JavaScript Application

The following program code describes the working of a chat application using JavaScript and Web Socket protocol.

<!DOCTYPE html>
<html lang = "en">

   <head>

WebSockets - Communicating with Server

The Web has been largely built around the request/response paradigm of HTTP. A client loads up a web page and then nothing happens until the user clicks onto the next page. Around 2005, AJAX started to make the web feel more dynamic. Still, all HTTP communication is steered by the client, which requires user interaction or periodic polling to load new data from the server.

WebSockets - Security

Protocol should be designed for security reasons. WebSocket is a brand-new protocol and not all web browsers implement it correctly. For example, some of them still allow the mix of HTTP and WS, although the specification implies the opposite. In this chapter, we will discuss a few common security attacks that a user should be aware of.

WebSockets - Mobile APP

WebSocket, as the name implies, is something that uses the web. The web is usually interwoven with browser pages because that are the primary means of displaying data online. However, non-browser programs too, use online data transmission.

WebSockets - Overview

WebSockets - Useful Resources

The following resources contain additional information on WebSockets. Please use them to get more in-depth knowledge on this topic.

Discuss WebSockets

Web sockets are defined as a two-way communication between the servers and the clients, which mean both the parties, communicate and exchange data at the same time. This protocol defines a full duplex communication from the ground up.

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Sunday, March 19, 2017